Micro LED display system

ABSTRACT

MicroLED arrays offer a small form factor solution for the HMD image sources since they do not need a separate illumination optics. Features of the present disclosure implement a MicroLED display system that incorporate a plurality of monochrome projectors (e.g., three MicroLED projectors) to generate three monochrome images (e.g., red, blue, and green images) that are separately input into a single waveguide of the HMD and combined to form an image that is displayed to the user. By utilizing a single waveguide that includes a plurality of spatially separated input regions (e.g., a region for inputting blue light, a region for inputting red light, a region for inputting green light), the MicroLED display system of the present disclosure may reduce the form factor of the HMD device because of the reduced number of plates that may be required to combine the three monochrome images.

BACKGROUND

The present disclosure relates to computer graphics systems, and moreparticularly, to a Micro light emitting diode (MicroLED) display systemand the color management of the display device.

One area of computing devices that has grown in recent years is the areaof virtual reality (VR) and augmented reality (AR) devices, which use agraphics processing unit (GPU) to render graphics from a computingdevice to a display device. Such technology may be incorporated into ahead-mounted display (HMD) device in the form of eyeglasses, goggles, ahelmet, a visor, or other eyewear. As used herein, a HMD device mayinclude a device that generates and/or displays virtual reality images(e.g., from at least one virtual environment input), and/or mixedreality (MR) images or augmented reality (AR) images (e.g., from atleast one virtual environment input and one real environment input). Insuch devices, a scene produced on a display device can be oriented ormodified based on user input (e.g., movement of a gamepad button orstick to cause movement of the orientation of the scene, introduction ofitems into the scene, etc.).

One challenge with incorporating display devices into HMD or mobiledevices is the size constraints that limit some of the optical ordisplay components that can be integrated into the HMD devices whileminiaturizing the overall size of the HMD devices to improve usermobility. Current HMDs usually use illuminated micro displays such asreflective liquid crystal on silicon (hereafter “LCoS”) or digital lightprocessing (DLP) projectors as they provide a high standard of displayperformance. These displays offer advantages such as high resolution, awide color gamut, high brightness and a high contrast ratio. However,such digital projection systems that rely on LCoS or DLP technologyrequire large form factors to create a uniform illumination of panels.Thus, there is a need in the art for improvements in presenting imageson a display with miniaturized components without compromising thedisplay quality or user experience.

SUMMARY

MicroLED arrays offer a small form factor solution for the HMD imagesources since they do not need separate illumination optics. Features ofthe present disclosure implement a MicroLED display system thatincorporates a plurality of monochrome projectors (e.g., three MicroLEDprojectors) to generate three monochrome images (e.g., red, blue, andgreen images) that are separately input into a single waveguide of theHMD and combined to form an image that is displayed to the user. Byutilizing a single waveguide that includes a plurality of spatiallyseparated input regions (e.g., a region for inputting blue light, aregion for inputting red light, and a region for inputting green light),the MicroLED display system of the present disclosure may reduce theform factor of the HMD device because of the reduced number and/or sizeof optical components, such as a reduced number of plates that may berequired to combine the three monochrome images.

In one example, a display device is disclosed. The display device mayinclude an optical waveguide having a plurality of input regions forreceiving at least a portion of light corresponding to an image, whereinthe plurality of input regions include at least a first input region, asecond input region, and a third input region. The display device mayalso include a plurality of monolithic micro light emitting diode(MicroLED) projectors that each generate a different monochrome colorversion of the image. In some examples, the plurality of MicroLEDprojectors may include at least a first projector generating a firstversion of the image in a first color, a second projector generating asecond version of the image in a second color, and a third projectorgenerating a third version of the image in a third color. In someaspects, the first input region of the optical waveguide may bephysically aligned with the first projector to receive lightcorresponding to the first version of the image, the second input regionof the optical waveguide may be physically aligned with the secondprojector to receive light corresponding to the second version of theimage, and the third input region of the optical waveguide may bephysically aligned with the third projector to receive lightcorresponding to the third version of the image. In some examples, theoptical waveguide may further include an output region configured toguide light from each of the plurality of MicroLED projectors toward atarget to make a final image visible to user, wherein the final image isa fully colored image that combines the different monochrome colorversions of the image.

In another example, a method for displaying an image on a display deviceis disclosed. The method may include generating a plurality ofmonochrome color versions of an image using a plurality of monolithicMicroLED projectors, wherein the plurality of MicroLED projectorsincludes at least a first projector generating a first version of theimage in a first color, a second projector generating a second versionof the image in a second color, and a third projector generating a thirdversion of the image in a third color. The method may further includereceiving, at an optical waveguide, light inputs from each of theplurality of MicroLED projectors into a plurality of different inputregions of the optical waveguide such that a first input region of theoptical waveguide is physically aligned with a first color projector toreceive light corresponding to the first version of the image, thesecond input region of the optical waveguide is physically aligned withthe second color projector to receive light corresponding to the secondversion of the image, and the third input region of the opticalwaveguide is physically aligned with the third color projector toreceive light corresponding to the third version of the image. Themethod may further include outputting, through the optical waveguide,light from each of the plurality of MicroLED projectors toward a targetto make a final image visible to user, wherein the final image is afully colored image that combines the plurality of monochrome colorversions of an image.

In another example, another method for calibrating an image on a displaydevice is disclosed. The method may include detecting, at a camera,light rays output from an optical waveguide, wherein the light rayscorrespond to a plurality of monochrome color versions of an imagegenerated by a plurality of monolithic MicroLED projectors. The methodmay further include determining a first position of a first version ofthe image from the plurality of monochrome color versions of the image,wherein the first version of the image is generated in first monochromecolor by a first projector. The method may further include determining asecond position of a second version of the image from the plurality ofmonochrome color versions of the image, wherein the second version ofthe image is generated in second monochrome color by a second projector.The method may further include measuring an image displacement betweenthe first position of the first version of the image and the secondposition of the second version of the image to calculate an offset valuebetween the first position and the second position, wherein the imagedisplacement is one or both of lateral displacement or angularrotational displacement. The method may further include configuring thedisplay device to adjust at least one image output parameter of theplurality of MicroLED projectors such that the output from the opticalwaveguide of the plurality of monochrome color versions of the imagehave an overlapping alignment that meets an alignment threshold.

In another example, an apparatus for calibrating an image on a displaydevice is disclosed. The apparatus may include a memory to store dataand instructions. The apparatus may further include a processor incommunication with the memory to execute the instructions to detect, ata camera, light rays output from an optical waveguide, wherein the lightrays correspond to a plurality of monochrome color versions of an imagegenerated by a plurality of monolithic MicroLED projectors. Theapparatus may further include instructions to determine a first positionof a first version of the image from the plurality of monochrome colorversions of the image, wherein the first version of the image isgenerated in first monochrome color by a first projector. The apparatusmay further include instructions to determine a second position of asecond version of the image from the plurality of monochrome colorversions of the image, wherein the second version of the image isgenerated in second monochrome color by a second projector. Theapparatus may further include instructions to measure an imagedisplacement between the first position of the first version of theimage and the second position of the second version of the image tocalculate an offset value between the first position and the secondposition, wherein the image displacement is one or both of lateraldisplacement or angular rotational displacement. The apparatus mayfurther include instructions to configure the display device to adjustat least one image output parameter of the plurality of MicroLEDprojectors such that the output from the optical waveguide of theplurality of monochrome color versions of the image have an overlappingalignment that meets an alignment threshold.

The above presents a simplified summary of one or more implementationsof the present disclosure in order to provide a basic understanding ofsuch implementations. This summary is not an extensive overview of allcontemplated implementations, and is intended to neither identify key orcritical elements of all implementations nor delineate the scope of anyor all implementations. Its sole purpose is to present some concepts ofone or more implementations of the present disclosure in a simplifiedform as a prelude to the more detailed description that is presentedlater.

To the accomplishment of the foregoing and related ends, the one or moreaspects comprise the features hereinafter fully described andparticularly pointed out in the claims. The following description andthe annexed drawings set forth in detail certain illustrative featuresof the one or more aspects. These features are indicative, however, ofbut a few of the various ways in which the principles of various aspectsmay be employed, and this description is intended to include all suchaspects and their equivalents.

DESCRIPTION OF THE FIGURES

The disclosed aspects of the present disclosure will hereinafter bedescribed in conjunction with the appended drawings, provided toillustrate and not to limit the disclosed aspects, wherein likedesignations denote like elements, where a dashed line may indicate anoptional component, and in which:

FIG. 1A is a schematic diagram of a display device (e.g., HMD device) inaccordance with an implementation of the present disclosure;

FIGS. 1B and 1C are a schematic diagram of a side view of the displaydevice, and more particularly the waveguide aligned with a plurality ofmonochrome MicroLED projectors in accordance with an implementation ofthe present disclosure;

FIG. 2 is an example of light projection from a MicroLED projector to anoptical waveguide in accordance with an implementation of the presentdisclosure;

FIG. 3 is an example MicroLED display system that incorporate aplurality of monochrome MicroLED projectors to generate three monochromeimages that are separately input into a single waveguide of the HMD inaccordance with an implementation of the present disclosure;

FIG. 4 is another example MicroLED display system that incorporate aplurality of monochrome MicroLED projectors to generate three monochromeimages that are separately input into a single waveguide of the HMDwhile allowing at least two of the MicroLED projectors to share the samegrating structure in accordance with an implementation of the presentdisclosure;

FIG. 5 is a flow chart of a method for displaying images on a displaydevice in accordance with an implementation of the present disclosure;

FIG. 6 is a flow chart of a method for calibrating images on a displaydevice in accordance with an implementation of the present disclosure;

FIG. 7 is a schematic block diagram of an example device in accordancewith an implementation of the present disclosure.

DETAILED DESCRIPTION

Various aspects are now described with reference to the drawings. In thefollowing description, for purposes of explanation, numerous specificdetails are set forth in order to provide a thorough understanding ofone or more aspects. It may be evident, however, that such aspect(s) maybe practiced without these specific details. Additionally, the term“component” as used herein may be one of the parts that make up asystem, may be hardware, firmware, and/or software stored on acomputer-readable medium, and may be divided into other components.

The present disclosure provides devices and methods for presentation ofimages such as virtual reality (VR) or mixed reality (MR)/augmentedreality (AR) images on a display that is incorporated into mobiledisplay devices, such as displays implemented for head mounted display(HMD). It should be appreciated by those of ordinary skill in the artthat while the present disclosure references HMD, the display techniquesimplemented herein may be adaptable for any mobile device, including butnot limited to, mobile phones, tablets, or laptops.

As discussed above, one challenge with incorporating display devicesinto mobile devices is the size constraints that limit the componentsthat can be integrated into the display systems while miniaturizing theoverall size of the HMD devices or mobile display to improve usermobility. Current HMDs generally use illuminated micro displays such asreflective LCoS or DLP projectors as they provide a high standard ofdisplay performance. While these displays offer advantages such as highresolution, a wide color gamut, high brightness and a high contrastratio, such digital projection systems that rely on LCoS or DLPtechnology also require large form factors to create a uniformillumination of panels.

In contrast, MicroLED arrays offer a small form factor solution for theHMD image sources since they do not need separate illumination optics.However, the materials required to create semiconductors with eitherblue-green or red LEDs are generally incompatible in the manufacturingprocess of LEDs for specific colors (e.g., Indium, Gallium and Nitrogen(InGaN) to produce green, blue and white colors and/or Aluminum GalliumArsenide (AlGaAs) used to generate red and amber portions of the visiblespectrum). Specifically, from the manufacturing perspective, it may bedifficult to get all three colors into the same array without either thelabor intensive process of picking and placing each LED individually ordeveloping an expensive growth/lithography process.

One solution to the above-identified problem with MicroLED microdisplays may be to separate each of the red, green, and blue arrays andcombine the different colors with optics. However, optical combinersrequire large prism cubes to combine three different images together andrelay optics to prevent the divergence of the pixels when combining thecolors. Thus, such optical systems increase the optics footprint andprevent small form factor HMD development with micro LEDs. Furthermore,the divergence angle of the microLEDs may be so large (E.g., +/−40degrees) that it may impact the optical power.

Features of the present disclosure implement a MicroLED display systemthat incorporates a plurality of monochrome projectors (e.g., threeMicroLED projectors) to generate three monochrome images (e.g., red,blue, and green images) that are separately input into a singlewaveguide of the HMD and combined to form an image that is displayed tothe user. By utilizing a single waveguide that includes a plurality ofspatially separated input regions (e.g., a region for inputting bluelight, a region for inputting red light, a region for inputting greenlight), the MicroLED display system of the present disclosure may reducethe size and form factor of the HMD device because of the reduced numberof plates that may be required to combine the three monochrome imagesand/or because of the reduced number of size of the optical components.However, it should be appreciated by those of ordinary skill in the artthat the features of the present disclosure are not limited to pluralityof projectors generating monochrome images. Instead, in some examples, asingle projector without external illumination may also generate andinput the full color image into the waveguide. Such system would providebenefit of simplistic hardware and reduced form factor in comparison tothe current digital projection systems that rely on LCoS or DLPtechnology that require large form factors to create a uniformillumination of panels.

Specifically, in accordance with aspects of the present disclosure,waveguides with gratings may provide a mechanism to combine severalimages together with the smallest possible form factor. With a separatemicroLED display for each primary color, the exit pupil of eachimage/color may be coupled into a single optical waveguide that bringsthe pupils on top of each other using pupil replication. Further, sincethe waveguide may be designed to act as a pupil expander of an augmentedreality (AR) display, the same optical waveguide may be used to relaythe image into the user's eye, thereby saving on additional hardware byusing the same integrated waveguide to combine the three colors togetherand to act as an AR-display. This may include configuring the waveguideto steer the incoming field-of-view (FoV) at least into two or moredirections in order to enable pupil expansion with a large FoV.

Additional advantages of the present disclosure may be the hardwaresimplicity that is required for HMD. For example, by incorporating aplurality of monochrome projectors (e.g., three MicroLED projectors) togenerate three monochrome images (e.g., red, blue, and green images)that are separately input into a single waveguide of the HMD, the opticsof each MicroLED projectors may be simpler because no mirrors or doubletlenses may be needed to avoid or correct chromatic aberration.

In addition, in some implementations, the present disclosure may furtherreduce the form factor of the HMD by implementing a color managementscheme that may include modifying the color resolution of each MicroLEDprojector. Specifically, the physical size of the MicroLED projector maydepend on the resolution/pixel count of the imaging system. Recognizingthat the human eye has the highest sensitivity for green light, theoverall form factor of the HMD may be further reduced by lowering thecolor resolution of blue and/or red colors, while increasing the colorresolution of green light for full resolution. To this end, due to lowercolor resolution requirements of one or more colors (blue and/or redcolor images), features of the present disclosure may further reduce thesize and complexity of hardware of the monolithic MicroLED projectors.Thus, the lower color resolution of the blue and/or red colors may becompensated by a higher resolution of green color to provide a user witha full resolution image while benefiting from reduced form factor of theoverall display system. Although the above example discusses loweringthe color resolution of blue and/or red color images, it should beappreciated that the modification of the color resolution is not limitedto only blue and/or red colors, but instead may be adapted for anynumber of colors. Additionally, in some examples, the techniques of thepresent disclosure may be applied to lowering the color resolution ofonly one color.

Finally, features of the present disclosure also provide techniques ofcalibrating the image to be displayed via the optical guide byconfiguring one or more MicroLED projectors. For example, any mechanicalmounting issues with the MicroLED projectors may change the angle of theprojected image, which in turn may cause pixels from that MicroLEDprojector to be in misplaced. Thus, any displacement between the threemonochrome images may result in a blurry image being displayed on thedisplay device. One technique to solve this problem may includemanipulating the incoming image in order to pre-correct the location ofone or more pixels in order to account for any disparity. Thus, in someaspects of the manufacturing process, a calibration procedure may beimplemented that may utilize a camera to be placed in front of theoptical waveguide (e.g., where a user's eye would otherwise be) toidentify how each color field is separated from one another, and toprovide configuration parameters to calibrate the image from the threeMicroLED projectors such that the three images overlap, generating acohesive final image to be displayed. To this end, features of thepresent disclosure may include techniques for pre-rotating andoffsetting at least one of the three monochromic images to correct forany misalignment in the mechanical assembly of the display device,including the MicroLED projectors.

The following description provides examples, and is not limiting of thescope, applicability, or examples set forth in the claims. Changes maybe made in the function and arrangement of elements discussed withoutdeparting from the scope of the disclosure. Various examples may omit,substitute, or add various procedures or components as appropriate. Forinstance, the methods described may be performed in an order differentfrom that described, and various steps may be added, omitted, orcombined. Also, features described with respect to some examples may becombined in other examples.

Turning first to FIGS. 1A-1C, an example display device 100 mayimplement display techniques in accordance with an present disclosure.In some examples, as illustrated, the display device 100 may be a headmounted device (HMD). However, for purposes of this disclosure, itshould be appreciated that the techniques described herein are notlimited only to HMD, but may also be implemented in other displaydevices, including, but not limited to, mobile phones, laptops,televisions, etc. For purposes of this disclosure, features of FIGS.1A-1C may be discussed contemporaneously.

A display device 100 may be configured to provide virtual reality images(e.g., from at least one virtual environment input), and/or mixedreality (MR) images or augmented reality (AR) images (e.g., from atleast one virtual environment input and one real environment input). Thedisplay device 100, when implemented as a HMD, may comprises a headpiecearranged to be worn on the user's head using a frame 105 (in the mannerof conventional spectacles), helmet or other fit system. The purpose ofthe fit system is to support the display and provide stability to thedisplay and other head borne systems such as tracking systems andcameras.

The display device 100 may include one or more optical components 115(e.g., one or more lenses), including one or more optical waveguides 130(see FIGS. 1B and 1C) that may allow the HMD to project images generatedby one or more MicroLED projectors 120. The one or more MicroLEDprojectors 120 may project images to be displayed on the opticalcomponents 115. In accordance with aspects of the present disclosure,the optical component 115 may include three monolithic MicroLEDprojectors 120 (e.g., a first monolithic MicroLED projector 120-a, asecond monolithic MicroLED projector 120-b, and a third monolithicMicroLED projector 120-c—See FIGS. 1B and 1C) that each generate adifferent monochrome color version of the same image. For purposes ofthis disclosure, the phrase “monochrome color version of an image” mayrefer to an image (e.g., photograph, video frame, picture, etc.)developed in varying tones of only one color. For example, a firstprojector 120-a may generate a first version of the image in a firstcolor (e.g., red), a second projector 120-b may generate a secondversion of the image in a second color (e.g., blue), and a thirdprojector may generate a third version of the image in a third color(e.g., green). In some examples, the MicroLED projectors 120 may bepositioned either at the temple portion of the HMD or near the nasalcavity. Thus, in some aspects, two MicroLED projectors 120 may bepositioned near the temple portion of the HMD device (e.g., the side ofthe head between the forehead and the ear—see dashed MicroLED projector120-N) and one MicroLED projector 120 at the nasal side of the HMD(e.g., at the nose bridge portion when the HMD is worn by the user).Alternatively, in some aspects, two MicroLED projectors 120 may bepositioned near the nasal side of the HMD, while the third MicroLEDprojector 120 may be positioned at the temple portion of the HMD. Ineach instance, the MicroLED projectors 120 may project the respectivemonochrome color versions of an image into one or more waveguides of theHMD. It should be further appreciated that, in such configuration, theplurality of MicroLED projectors 120 may be included on either the sameside of the waveguide (see e.g., FIG. 1B) or on opposite sides of thewaveguide (see e.g., FIG. 1C)

As illustrated in FIGS. 1B and 1C, the three MicroLED projectors 120 maybe either positioned together on one side, or in different groups onopposing sides, of the optical waveguide 130 to the extent that theprojectors 120 may be physically aligned with the input regions 140 ofthe optical waveguide 130. In some examples, the first MicroLEDprojector 120-a may generate the first version of the image in only redcolor tone, while the second MicroLED projector 120-b may generate thesecond version of the image in only blue color tone, and the thirdMicroLED projector 120-c may generate the third version of the image inonly green color tone, such that the images can be combined to form agamut of colors.

The optical components 115 may focus a user's vision on one or moreportions of one or more display panels 125, as shown in FIG. 1B. Thedisplay panels 125 may display one or more images (e.g., left eye imageand right eye image) based on signals received from the plurality ofmonolithic MicroLED projectors 120. The optics 115 may include left eyeoptics 115-L for focusing the user's left eye on the left eye image andright eye optics 115-R for focusing the user's right eye on the righteye image. For example, the optics 115 may focus the user's eyes on acentral portion of each of the left eye image and the right eye image.The user's brain may combine the images viewed by each eye to create theperception that the user is viewing a combined image.

In some examples, the optical components 115 may include a left andright optical components (e.g., left optical component 115-L and rightoptical component 115-R). The optical components 115 may useplate-shaped (usually planar) waveguides 130 for transmitting angularimage information to users' eyes as virtual images from image sources(e.g., light engine and/or MicroLED projectors 120) located out of theuser's line of sight 135. The image information may be input near oneend of the waveguides 130 and is output near another end of thewaveguides 130.

In some examples, the image information may propagate along the opticalwaveguides 130 as a plurality of angularly related beams that areinternally reflected along the waveguide. The optical waveguide 130 canbe either a hollow pipe with reflective inner surfaces or an integratorrod with total or partial internal reflection. Additionally oralternatively, the optical waveguide 130 may be a single opticalwaveguide with different input regions for inputting different colorlights from the three MicroLED projectors 120 or multiple opticalwaveguides or plates stacked on top of each other such that each opticalwaveguide may input a single color light (e.g., first optical waveguidefor accepting red color light from a first MicroLED projector, a secondoptical waveguide for accepting a blue color light from a secondMicroLED projector, and a third optical waveguide for accepting a greencolor light from the third MicroLED projector). In either instance, theoptical waveguide 130 may include an inside surface (facing the user'seye) and an outside surface (facing the ambient environment), with boththe inside and outside surfaces being exposed to air or another lowerrefractive index medium. As such the optical waveguide 130 may be atleast partially transparent so that the user can also view the ambientenvironment through the waveguide.

Diffractive optics may be used for injecting the image information intothe waveguides through a first range of incidence angles that areinternally reflected by the waveguides as well as for ejecting the imageinformation through a corresponding range of lower incidence angles forrelaying or otherwise forming an exit pupil behind the waveguides 130 ina position that can be aligned with the users' eyes 135. Both thewaveguides 130 and the diffractive optics at the output end of thewaveguides may be at least partially transparent so that the user canalso view the ambient environment through the waveguides 130, such aswhen the image information is not being conveyed by the waveguides orwhen the image information does not fill the entire field of view.

As discussed above, in some examples, the optical waveguide 130 may be asingle waveguide that may include plurality of input regions forreceiving at least a portion of light corresponding to an image from theone or more monolithic MicroLED projectors 120. In such instances, theability of a single optical waveguide 130 to accept input from threedifferent color lights produced by three MicroLED projectors 120 (e.g.,120-a, 120-b, and 120-c) may reduce the number of physical plates thatmay be used, and thereby reduce the physical size of the display device.The plurality of input regions may include at least a first input region140-a, a second input region 140-b, and a third input region 140-c. Insome instances, the first input region 140-a of the optical waveguide130 may be physically aligned with the first projector 120-a to receivelight corresponding to the first version of the image, the second inputregion 140-b of the optical waveguide 130 may be physically aligned withthe second projector 120-b to receive light corresponding to the secondversion of the image, and the third input region 140-c of the opticalwaveguide 130 may be physically aligned with the third projector 120-cto receive light corresponding to the third version of the image.Further, the optical waveguide 130 may include an output region 145configured to guide light from each of the plurality of MicroLEDprojectors 120 toward a target to make a final image visible to user'seye 135, wherein the final image is a fully colored image that combinesthe different monochrome color versions of the image.

In some aspects, the first input region 140-a, the second input region140-b, and the third input region 140-c may be configured toindependently receive the first version of the image, the second versionof the image, and the third version of the image, respectively, and theoptical waveguide 130 may include a plurality of diffractive opticalelements configured to combine the first version of the image, thesecond version of the image, and the third version of the image to formthe final image. In other words, features of the present disclosureprovide techniques for each of the plurality of monochrome images (e.g.,red, blue, and green) to be combined within the single optical waveguide130 without requiring separate hardware for the optical combiner, e.g.,large prisms to combine three different images together and relay opticsto prevent the divergence of the pixels when combining the colors.

In some aspects, each input region 140 of the optical waveguide 130 mayinclude a different grating structure. For example, the first inputregion 140-a of the optical waveguide 130 may include a first gratingstructure configured to cause a first amount of phase change uponreflection of the light corresponding to the first version of the image,while the second input region 140-b of the optical waveguide 130 mayinclude a second grating structure configured to cause a second amountof phase change upon reflection of the light corresponding to the secondversion of the image. Even further, in such instance, the third inputregion 140-c of the optical waveguide 130 may include a third gratingstructure configured to cause a third amount of phase change uponreflection of the light corresponding to the version of the image,wherein the first amount, the second amount, and the third amount aredifferent amounts.

By configuring each input region 140 with a different grating structureto separately reflect the light by varying degree of phase change foreach version of the image, the aspects of the present disclosure mayallow for the three monochrome images to overlap and align within thewaveguide to produce a final image that is a fully colored image.Specifically, in some instances, the first grating structure, the secondgrating structure, and the third grating structure may be arranged suchthat the light associated with each of the first version of the image,the second version of the image, and the third version of the imageoverlaps within the optical waveguide to produce the final image. Thus,in such instances, as illustrated in FIG. 1B and FIG. 3 (infra), thethree MicroLED projectors 120 may be mounted on the same side of theoptical waveguide 130 (either on the inside surface or the outsidesurface), each MicroLED projector 120 being physically aligned with adifferent input region 140 to receive light from the MicroLED projectors120.

Alternatively, in other examples—as illustrated in FIG. 1C—at least twoof the three MicroLED projectors 120 may share the same input region 140having a single grating structure to reduce the complexity of theoptical waveguide 130. For example, different monochrome light havingsimilar wavelengths, e.g., red and blue colors, may utilize the samewaveguide parameters (e.g., grating), where such collaboration may allowthe display device 100 to use the same grating regions for twoprojectors (e.g., first MicroLED projector 120-a and second MicroLEDprojector 120-b). In such instance, the first input region 140-a and thesecond input region 140-b of the optical waveguide may have a firstgrating structure which causes light to change phase upon reflection bya first amount, while the third input region 140-c of the opticalwaveguide 130 may have a second grating structure which causes light tochange phase upon reflection by a second amount.

Continuing with discussion with reference to FIG. 1C, in instances thatmultiple MicroLED projectors 120 share the same grating structure of theoptical waveguide 130, it may be difficult to manage spatial constraintsof having all three input regions 140 on the same architecture. In suchinstances, the two MicroLED projectors (e.g., first MicroLED projector120-a and second MicroLED projector 120-b) that share the same gratingarchitecture may be positioned on a first side of the optical waveguide130, whereas the third MicroLED projector 120-c may be physicallypositioned on a second side of the optical waveguide 130. Specifically,the first projector 120-a and the second projector 120-b may bephysically positioned at a first side of the optical waveguide 130 suchthat the light from the first projector 120-a and the second projector120-b is projected towards the first input grating structure, and thethird projector 120-c may be physically positioned at a second side ofthe optical waveguide such that the light from the third projector 120-cmay be projected towards the second grating structure of the opticalwaveguide, wherein the second side is opposite the first side, asillustrated in FIG. 1C. In some examples, the third input region 140-cmay overlap with at least one of the first input region 140-a or thesecond input region 140-b. It should be also appreciated that althoughFIG. 1C illustrates the first MicroLED projector 120-a and secondMicroLED projector 120-b on the inside of the optical waveguide 130(e.g., towards the position of the eye 135) and the third MicroLEDprojector 120-c on the outside of the optical waveguide 130, it ispossible to have the positioning reversed such that first MicroLEDprojector 120-a and second MicroLED projector 120-b may be positioned onthe outside of the optical waveguide 130, and the third MicroLEDprojector 120-c on the inside of the optical waveguide 130.

Though not shown in FIGS. 1A-1C, a processing apparatus 705, memory 710and other components may be integrated into the display device 100 (seeFIG. 7). Alternatively, such components may be housed in a separatehousing connected to the display device 100 by wired and/or wirelessmeans. For example, the components may be housed in a separate computerdevice (e.g., smartphone, tablet, laptop or desktop computer etc.) whichcommunicates with the display device 100. Accordingly, mounted to orinside the display device may be an image source, such as a plurality ofMicroLED projectors for projecting a virtual image onto the opticalcomponent 115.

Referring next to FIG. 2, an imaging unit 200 may map lightcorresponding each pixel (e.g., pixels 202, 204) of an image from spaceto angular reflecting input into an optical waveguide. In some aspects,the imaging unit 200 may be an example of a MicroLED projector 120described with reference to FIG. 1. Although, aspects of FIG. 2 describeimage projectors from a single projector, it should be appreciated thatthe same may be replicated for additional MicroLED projectors describedherein.

As illustrated, the image to be projected may be represented in angularspace where every angle reflects light at the input location of firstpixel 202 and second pixel 204. The imaging unit 200 (or MicroLEDprojector 120) may include a display panel 205 that may display theimage to be projected within the optical waveguide 130. Each dashed linein FIG. 2 may represent light rays coming from a different position onthe panel (e.g., from first pixel 202 at the border of the image and asecond pixel 204 from the middle region of the image). In order toensure that the user views the entire image, the imaging unit 200 maymanipulate one or more light rays through the optics 210 at variousangles such that the user views the entire image within the HMD systemregardless of where the eye of the user is looking within the HMD. Thus,as illustrated, in some aspects the boundary pixels may be managed withmore extensive manipulation of angle reflections through the optics 210than the pixels in the middle of the image (e.g., second pixel 204).

In this respect, the optical waveguide may reflect light associated witheach pixel (e.g., first light rays 215 associated with the first pixel202, and second light rays 220 associated with the second pixel 204)such that the image may be displayed to the user based on the where theeye would be at the output region of the optical waveguide.

Turning next to FIG. 3, an example MicroLED display system 300incorporate a plurality of monochrome MicroLED projectors 120 togenerate three monochrome versions of the same image (e.g., one in red,one in blue, one in green) that are separately input into a singlewaveguide 130 of the HMD in accordance with an implementation of thepresent disclosure. As discussed above, the optical waveguide 130 mayinclude a plurality of input regions 140 (also referred to asin-coupling elements) located in the region of the waveguide 130 toaccept input of light from the plurality of MicroLED projectors 120(e.g., at the user's nose bridge or temple when the HMD device is wornby the user). The input regions 140 may be formed from, for example, asurface diffraction grating, volume diffraction grating, or a refractivecomponent. The waveguide 130 may further include a single output region145 (also called out-coupling element) and a transmission channel.

In some aspects, the output port 310 of each MicroLED projector 120 maybe is optically coupled (but not necessarily physically coupled) to eachof the plurality of input regions 140 of the optical waveguide 130. Forexample, the first input region 140-a of the optical waveguide 130 maybe physically aligned and optically coupled (but not physically coupled)with the first MicroLED projector 120-a to receive light correspondingto the first version of the image output from the first output port310-a of the first MicroLED projector 120-a. Similarly, the second inputregion 140-b of the optical waveguide 130 may be physically aligned andoptically coupled with the second MicroLED projector 120-b to receivelight corresponding to the second version of the image output from thesecond output port 310-b of the second MicroLED projector 120-b.Finally, the third input region 140-c of the optical waveguide 130 maybe physically aligned and optically coupled with the third MicroLEDprojector 120-c to receive light corresponding to the third version ofthe image output from the third output port 310-c of the third MicroLEDprojector 120-c.

The optical waveguide 130 may further include an output region 145configured to guide light from each of the plurality of MicroLEDprojectors 120 toward a target (e.g., a user's eye) to make a finalimage visible to user, wherein the final image is a fully colored imagethat combines the different monochrome color versions of the image. Insome instances, each of the plurality of input regions 140 mayindependently receive each of the three versions of the monochromeimages from the plurality of MicroLED projectors 120 such that theoptical waveguide 140 may combine the first version of the image, thesecond version of the image, and the third version of the image to formthe final image by ensuring that the light from each of the differentversions of the image overlap.

The optical waveguide 130 may achieve the overlapping image bycombination of different grating structures for different input regions,and by nature of the replication process that allow the images to stackup on top of each other upon entering the optical waveguide 130. Asdiscussed above, in some instances, minor calibration corrections may berequired to be performed in order to ensure that the three differentversions of the image overlap to form a high resolution image to beoutput from the output region 145.

For the calibration process, features of the present disclosure mayutilize a camera in position of an eye to detect light rays output froman optical waveguide 130. The light rays may correspond to a pluralityof monochrome color versions of an image generated by a plurality ofmonolithic MicroLED projectors. Upon detecting the light rays outputfrom the output region 145, the image calibration component 735 (seeFIG. 7) of the present disclosure may determine a first position of afirst version of the image and determine a second position of a secondversion of the image from the plurality of monochrome color versions ofthe image. Based on identification of the position of each version ofthe image, the image calibration component 735 may measure an imagedisplacement between the first position of the first version of theimage and the second position of the second version of the image tocalculate an offset value between the first position and the secondposition. In some examples, the image displacement is one or both oflateral displacement or angular rotational displacement. Thus, based onthe measurement, the image calibration component 735 of the presentdisclosure may configure the display device to adjust at least one imageoutput parameter of the plurality of MicroLED projectors 120 such thatthe output from the optical waveguide of the plurality of monochromecolor versions of the image have an overlapping alignment that meets analignment threshold.

For example, if the image calibration component 735 detects a pixeldisplacement of 20 microns between the first version of the image (e.g.,the version produced by green MicroLED projector) and a second versionof the image (e.g., the version produced by the blue MicroLEDprojector), the camera may be configured to detect such displacement andconfigure one of the MicroLED projectors 120 (e.g., the green MicroLEDprojector) to offset the green images by 5 pixels. Thus, instead ofstarting the green image at pixel position 0, the calibration processmay offset the green image to pixel 5 position such that the green imageand the blue image align or overlap when output from the opticalwaveguide 130.

Additionally, in some examples, each input region 140 of the opticalwaveguide 130 may have a different grating structure to cause differentvariation of phase change upon reflection of light that is input intothe optical waveguide 130. For example, in some instances, the firstinput region 140-a of the optical waveguide 130 may include a firstgrating structure configured to cause a first amount of phase changeupon reflection of the light corresponding to the first version of theimage, the second input region 140-b of the optical waveguide 130 mayinclude a second grating structure configured to cause a second amountof phase change upon reflection of the light corresponding to the secondversion of the image, and the third input region 140-c of the opticalwaveguide 130 may include a third grating structure configured to causea third amount of phase change upon reflection of the lightcorresponding to the version of the image. In some aspects, of the firstamount, the second amount, and the third amount may be different amountsthat result in all three versions of the image to overlap within theoptical guide 130.

In other instances, such as in FIG. 4, a MicroLED display system 400 mayincorporate a plurality of monochrome MicroLED projectors 120 togenerate three monochrome images that are separately input into a singlewaveguide 130 of the HMD, but allowing for at least two of the MicroLEDprojectors (e.g., first MicroLED projector 120-a and second MicroLEDprojector 120-b) to share the same grating structure in accordance withan implementation of the present disclosure. In such instance, the firstinput region 140-a and the second input region 140-b of the opticalwaveguide 130 may have a first grating structure (e.g., similar gratingparameters) which causes light to change phase upon reflection by afirst amount, and the third input region 140-c of the optical waveguide130 may have a second grating structure which causes light to changephase upon reflection by a second amount. In such instance, the firstprojector 120-a and the second projector 120-b may be physicallypositioned at a first side of the optical waveguide 130 such that thelight from the first projector 120-a and the second projector 120-b isprojected towards the first input grating structure. In samearchitecture, the third projector 120-c may be physically positioned ata second side of the optical waveguide 130 such that the light from thethird projector 120-c may be projected towards the second gratingstructure of the optical waveguide. In some examples, as illustrated inFIG. 4, the second side of the optical waveguide 130 may be opposite tothe first side.

In such instances, there may be a number of reasons that the projectors120 may be positioned on the opposite sides of the waveguide 130. First,in general, the lateral dimensions of the projector 120 may be largerthan the output stream. Thus, in order to handle the spatial constraintsof mounting the projectors within the display device, it may benecessary to physically separate the projectors 120 to differentportions of the optical waveguide. However, it should be appreciatedthat such separation may not only be limited to positioning theprojectors 120 on opposite sides, but may also be on the same side butdifferent ends of the optical waveguide 130. Second, the projectors maybe spatially separated in order to allow multiple colors (e.g., blue andred) to work with the same waveguide parameters (e.g., to be projectedonto the same grating regions). Thus, in such instance, the firstprojector 120-a and the second projector 120-b may be physically alignedwith the first input region 140-a and second input region 140-b thatboth share the same grating structure. Meanwhile, the third projector120-c may be physically aligned with the third input region 140-c thatis spatially separated from the first and second input regions (140-aand 140-b). Third, by placing two projectors on one side and theremaining projector on the other side of the waveguide, the opposinginput regions may overlap, thereby reducing the area taken up by theinput regions and/or the space taken up by the projectors. Sucharchitecture allows the display device 100 to achieve smaller formfactor and simpler hardware configuration.

Referring next to FIG. 5, method 500 for displaying an image on adisplay device is described. In some examples, the display device may bea HMD 105. However, it should also be appreciated that the features ofthe method 500 may be incorporated not only in the HMD 105 technology,but also other display devices such as mobile phones, tablets, orlaptops. Although the method 500 is described below with respect to theelements of the display device, other components may be used toimplement one or more of the steps described herein.

At block 505, the method 500 may include generating a plurality ofmonochrome color versions of an image using a plurality of monolithicMicroLED projectors. In some examples, the plurality of MicroLEDprojectors may include at least a first projector generating a firstversion of the image in a first color, a second projector generating asecond version of the image in a second color, and a third projectorgenerating a third version of the image in a third color. In someexamples, the first projector may generate the first version of theimage in only red color tone, the second projector may generate thesecond version of the image in only blue color tone, and the thirdprojector may generate the third version of the image in only greencolor tone. Aspects of block 505 may be performed by a plurality ofMicroLED projectors 305-a, 305-b, and 305-c in conjunction withrendering component 730 described with reference to FIGS. 3 and 7.

At block 510, the method 500 may include receiving, at an opticalwaveguide, light inputs from each of the plurality of MicroLEDprojectors into a plurality of different input regions of the opticalwaveguide such that a first input region of the optical waveguide isphysically aligned with a first color projector to receive lightcorresponding to the first version of the image, the second input regionof the optical waveguide is physically aligned with the second colorprojector to receive light corresponding to the second version of theimage, and the third input region of the optical waveguide is physicallyaligned with the third color projector to receive light corresponding tothe third version of the image. In some examples, the optical waveguidemay have a plurality of internally reflective surfaces to enable lightrays of a plurality of different colors generated by the plurality ofMicroLED projectors to propagate through its substrate by total internalreflection.

Further, in some examples, the first input region, the second inputregion, and the third input region may be configured to independentlyreceive the first version of the image, the second version of the image,and the third version of the image, respectively. Further, in suchsituation, the optical waveguide may include a plurality of diffractiveoptical elements configured to combine the first version of the image,the second version of the image, and the third version of the image toform the final image.

For example, the first input region of the optical waveguide may includea first grating structure configured to cause a first amount of phasechange upon reflection of the light corresponding to the first versionof the image. Further, in some examples, the second input region of theoptical waveguide may include a second grating structure configured tocause a second amount of phase change upon reflection of the lightcorresponding to the second version of the image, and the third inputregion of the optical waveguide may include a third grating structureconfigured to cause a third amount of phase change upon reflection ofthe light corresponding to the version of the image, wherein the firstamount, the second amount, and the third amount are different amounts.In such instances, the first grating structure, the second gratingstructure, and the third grating structure may be arranged such that thelight associated with each of the first version of the image, the secondversion of the image, and the third version of the image overlaps withinthe optical waveguide to produce the final image

In other instances, the first input region and the second input regionof the optical waveguide may have a first grating structure which causeslight to change phase upon reflection by a first amount, and the thirdinput region of the optical waveguide may have a second gratingstructure which causes light to change phase upon reflection by a secondamount. In other words, in some examples, two colors (e.g., lightassociated with the first color and the second color image, where thefirst color is red and second color is blue) may share the samewaveguide parameters (e.g., grating structure). In such situations,features of the present disclosure may allow use of a single gratingregions for two projectors (e.g., projectors generating the red colormonochrome image and the blue color monochrome image) and a separatewaveguide parameter for the third projector (e.g., projector generatingthe green color monochrome image).

By sharing the waveguide parameters for at least two projectors,features of the present disclosure may further reduce the size of theHMD. In order to ensure such implementation, aspects of the presentdisclosure may configure the first projector and the second projector tobe physically positioned at a first side of the optical waveguide suchthat the light from the first projector and the second projector isprojected towards the first input grating structure, and the thirdprojector may be physically positioned at a second side of the opticalwaveguide such that the light from the third projector is projectedtowards the second grating structure of the optical waveguide, whereinthe second side is opposite the first side. In some examples, the thirdinput region may overlap with at least one of the first input region orthe second input region. Aspects of block 510 may be performed by thedisplay such as an optical waveguide 52 described with references toFIGS. 1-3 and 7.

At block 515, the method 500 may include outputting, through the opticalwaveguide, light from each of the plurality of MicroLED projectorstoward a target to make a final image visible to user, wherein the finalimage is a fully colored image that combines the plurality of monochromecolor versions of an image. Aspects of the 515 may also be performed bythe display such an optical waveguide 52 that may include an outputregion for allowing light to exit to user's eye displaying the renderedimage.

Turning next to FIG. 6, method 600 for calibrating an image on a displaydevice is described. As discussed above, the features of the method 600may be incorporated not only in the HMD 105 technology, but also otherdisplay devices such as mobile phones, tablets, or laptops. Although themethod 600 is described below with respect to the elements of thedisplay device, other components may be used to implement one or more ofthe steps described herein.

At block 605, the method 600 may include detecting, at a camera, lightrays output from an optical waveguide, wherein the light rays correspondto a plurality of monochrome color versions of an image generated by aplurality of monolithic MicroLED projectors. In some examples, theplurality of MicroLED projectors may include at least the firstprojector for generating images in the first monochrome color, thesecond projector for generating images in the second monochrome color,and a third projector for generating images in a third monochrome color.Aspects of block 605 may be performed by the user interface component720 described with reference to FIG. 7. In some examples, the userinterface 720 may include a camera for detecting light output from theoptical waveguide. It should also be appreciated that, in some examples,a camera may be a separate hardware removed from the image displaydevice.

At block 610, the method 600 may include determining a first position ofa first version of the image from the plurality of monochrome colorversions of the image, wherein the first version of the image isgenerated in first monochrome color by a first projector. In someexamples, the optical waveguide receives the first version of the imageat a first input region of the optical waveguide. The first input regionof the optical waveguide may be physically aligned with the firstprojector. Aspects of block 610 may be performed by the imagecalibration component 735 described with reference to FIG. 7.

At block 615, the method 600 may include determining a second positionof a second version of the image from the plurality of monochrome colorversions of the image, wherein the second version of the image isgenerated in second monochrome color by a second projector. In someexamples, the optical waveguide may receive the second version of theimage at a second input region of the optical waveguide. The secondinput region of the optical waveguide may be physically aligned with thesecond projector. In some instances, the first input region and thesecond input region are configured to independently receive the firstversion of the image and the second version of the image, respectively,and wherein the optical waveguide may further include a plurality ofdiffractive optical elements configured to combine the first version ofthe image and the second version of the image to form a final image. Inother words, features of the present disclosure allow the threemonochrome images to be merged into a single image within the singlewaveguide without requiring prisms and other hardware to combine thethree separate images prior to inputting the light into the opticalwaveguide. Aspects of block 610 may be performed by the imagecalibration component 735 described with reference to FIG. 7.

At block 620, the method 600 may include measuring an image displacementbetween the first position of the first version of the image and thesecond position of the second version of the image to calculate anoffset value between the first position and the second position, whereinthe image displacement is one or both of lateral displacement or angularrotational displacement. Aspects of block 620 may be performed by theimage displacement component 740 described with reference to FIG. 7.

At block 625, the method 600 may include configuring the display deviceto adjust at least one image output parameter of the plurality ofMicroLED projectors such that the output from the optical waveguide ofthe plurality of monochrome color versions of the image have anoverlapping alignment that meets an alignment threshold. In someexamples, configuring the display device may adjust at least one imageoutput parameter includes correcting pixel spacing between the firstposition of the first version of the image and the second position ofthe second version of the image by shifting a start position of at leastone of the first version of the image or the second version of theimage.

In some examples, configuring the display device may further includeadjusting a color resolution of the plurality of MicroLED projectors,including lowering the color resolution of the first monochrome colorgenerated by the first projector and/or the second monochrome colorgenerated by the second projector, while increasing the color resolutionof the third monochrome color generated by the third projector. Forexample, in instances the first monochrome color may be red color toneof the image, the second monochrome color may be blue color tone of theimage, and the third monochrome color is green color tone of the image,the display device may be able to lower the resolution for blue and/orred, and increase the resolution for the green color. Because the humaneye has the highest sensitivity for green light, the display device maybe able to display a high resolution image by compensating the lowerblue and/or red resolution with an image processing with the highergreen resolution. Due to lower blue and/or red resolutions, the formfactor of the blue and/or red imaging system may be significantlyreduced (e.g., reduction of factor of four in some instances). Thus, thesmaller form factor for two of the three projectors may allow the HMD tohave a smaller size and form factor. Aspects of block 625 may beperformed by the projector configuration component 745 described withreference to FIG. 7. Additionally, as discussed above, although theexample herein discusses lowering the color resolution of blue and/orred color images, it should be appreciated that the modification of thecolor resolution is not limited to only blue and/or red colors, butinstead may be adapted for any color. Additionally, in some examples,the techniques of the present disclosure may be applied to lowering thecolor resolution of only one color as opposed to two colors.

Referring now to FIG. 7, a diagram illustrating an example of a hardwareimplementation for displaying an image frame on a display device (e.g.,HMD) in accordance with various aspects of the present disclosure isdescribed. In some examples, the image display device 400 may be anexample of the HMD 105 described with reference to FIGS. 1A and 1B.

The image display device 400 may include a processor 405 for carryingout one or more processing functions (e.g., methods 500 and 600)described herein. The processor 705 may include a single or multiple setof processors or multi-core processors. Moreover, the processor 705 canbe implemented as an integrated processing system and/or a distributedprocessing system.

The image display device 700 may further include memory 710, such as forstoring local versions of applications being executed by the processor705. In some aspects, the memory 710 may be implemented as a singlememory or partitioned memory. In some examples, the operations of thememory 710 may be managed by the processor 705. Memory 710 can include atype of memory usable by a computer, such as random access memory (RAM),read only memory (ROM), tapes, magnetic discs, optical discs, volatilememory, non-volatile memory, and any combination thereof. Additionally,the processor 705, and memory 710 may include and execute operatingsystem (not shown).

Further, the image display device 700 may include a communicationscomponent 715 that provides for establishing and maintainingcommunications with one or more parties utilizing hardware, software,and services as described herein. Communications component 715 may carrycommunications between components on image display device 705. Thecommunications component 715 may also facilitate communications withexternal devices to the image display device 700, such as to electronicdevices coupled locally to the image display device 700 and/or locatedacross a communications network and/or devices serially or locallyconnected to image display device 700. For example, communicationscomponent 715 may include one or more buses operable for interfacingwith external devices. In some examples, communications component 715establish real-time video communication events, via the network, withanother user(s) of the communication system operating their own devicesrunning their own version of the communication client software in orderto facilitate augmented reality.

The image display device 700 may also include a user interface component720 operable to receive inputs from a user of display device 700 andfurther operable to generate outputs for presentation to the user. Userinterface component 720 may include one or more input devices, includingbut not limited to a navigation key, a function key, a microphone, avoice recognition component, joystick or any other mechanism capable ofreceiving an input from a user, or any combination thereof. Further,user interface component 720 may include one or more output devices,including but not limited to a speaker, headphones, or any othermechanism capable of presenting an output to a user, or any combinationthereof.

The image display device 700 may include a rendering component 730 thatcontrols the light engine(s) to generate an image visible to the wearerof the HMD, i.e. to generate slightly different 2D or 3D images that areprojected onto the waveguide so as to create the impression of 3Dstructure. In some examples, the rendering component 730 may beconfigured to generate a plurality of monochrome color versions of animage using a plurality of monolithic MicroLED projectors, wherein theplurality of MicroLED projectors includes at least a first projectorgenerating a first version of the image in a first color, a secondprojector generating a second version of the image in a second color,and a third projector generating a third version of the image in a thirdcolor. The rendering component 730 may also input light, at an opticalwaveguide, inputs from each of the plurality of MicroLED projectors intoa plurality of different input regions of the optical waveguide suchthat a first input region of the optical waveguide is physically alignedwith a first color projector to receive light corresponding to the firstversion of the image, the second input region of the optical waveguideis physically aligned with the second color projector to receive lightcorresponding to the second version of the image, and the third inputregion of the optical waveguide is physically aligned with the thirdcolor projector to receive light corresponding to the third version ofthe image.

The image display device 700 may further include a display 52 that maybe an example of the optics 115 or waveguide 210 described withreference to FIGS. 1A, 1B and 2. In some examples, the display 52 may beconfigured to output, through the optical waveguide, light from each ofthe plurality of MicroLED projectors toward a target to make a finalimage visible to user, wherein the final image is a fully colored imagethat combines the plurality of monochrome color versions of an image.

The image display device 700 may further an image calibration component735. In some examples, the image calibration component 735 may beconfigured to detect, at a camera, light rays output from an opticalwaveguide, wherein the light rays correspond to a plurality ofmonochrome color versions of an image generated by a plurality ofmonolithic MicroLED projectors. The image calibration component 735 mayfurther be configured to determine a first position of a first versionof the image from the plurality of monochrome color versions of theimage, wherein the first version of the image is generated in firstmonochrome color by a first projector. The image calibration component735 may further be configured to determine a second position of a secondversion of the image from the plurality of monochrome color versions ofthe image, wherein the second version of the image is generated insecond monochrome color by a second projector. The image calibrationcomponent 735, and more particularly, the image displacement component740 may be configured to measure an image displacement between the firstposition of the first version of the image and the second position ofthe second version of the image to calculate an offset value between thefirst position and the second position, wherein the image displacementis one or both of lateral displacement or angular rotationaldisplacement.

The image calibration component 735 may also include a projectorconfiguration component 745 to configure the display device to adjust atleast one image output parameter of the plurality of MicroLED projectorssuch that the output from the optical waveguide of the plurality ofmonochrome color versions of the image have an overlapping alignmentthat meets an alignment threshold. In some examples, configuring thedisplay device may adjust at least one image output parameter includingcorrecting pixel spacing between the first position of the first versionof the image and the second position of the second version of the imageby shifting a start position of at least one of the first version of theimage or the second version of the image.

As used in this application, the terms “component,” “system” and thelike are intended to include a computer-related entity, such as but notlimited to hardware, firmware, a combination of hardware and software,software, or software in execution. For example, a component may be, butis not limited to being, a process running on a processor, a processor,an object, an executable, a thread of execution, a program, and/or acomputer. By way of illustration, both an application running on acomputing device and the computing device can be a component. One ormore components can reside within a process and/or thread of executionand a component may be localized on one computer and/or distributedbetween two or more computers. In addition, these components can executefrom various computer readable media having various data structuresstored thereon. The components may communicate by way of local and/orremote processes such as in accordance with a signal having one or moredata packets, such as data from one component interacting with anothercomponent in a local system, distributed system, and/or across a networksuch as the Internet with other systems by way of the signal.

Furthermore, various aspects are described herein in connection with adevice, which can be a wired device or a wireless device. A wirelessdevice may be a cellular telephone, a satellite phone, a cordlesstelephone, a Session Initiation Protocol (SIP) phone, a wireless localloop (WLL) station, a personal digital assistant (PDA), a handhelddevice having wireless connection capability, a computing device, orother processing devices connected to a wireless modem. In contract, awired device may include a server operable in a data centers (e.g.,cloud computing).

It is understood that the specific order or hierarchy of blocks in theprocesses/flow charts disclosed is an illustration of exemplaryapproaches. Based upon design preferences, it is understood that thespecific order or hierarchy of blocks in the processes/flow charts maybe rearranged. Further, some blocks may be combined or omitted. Theaccompanying method claims present elements of the various blocks in asample order, and are not meant to be limited to the specific order orhierarchy presented.

The previous description is provided to enable any person skilled in theart to practice the various aspects described herein. Variousmodifications to these aspects will be readily apparent to those skilledin the art, and the generic principles defined herein may be applied toother aspects. Thus, the claims are not intended to be limited to theaspects shown herein, but is to be accorded the full scope consistentwith the language claims, wherein reference to an element in thesingular is not intended to mean “one and only one” unless specificallyso stated, but rather “one or more.” The word “exemplary” is used hereinto mean “serving as an example, instance, or illustration.” Any aspectdescribed herein as “exemplary” is not necessarily to be construed aspreferred or advantageous over other aspects. Unless specifically statedotherwise, the term “some” refers to one or more. Combinations such as“at least one of A, B, or C,” “at least one of A, B, and C,” and “A, B,C, or any combination thereof” include any combination of A, B, and/orC, and may include multiples of A, multiples of B, or multiples of C.Specifically, combinations such as “at least one of A, B, or C,” “atleast one of A, B, and C,” and “A, B, C, or any combination thereof” maybe A only, B only, C only, A and B, A and C, B and C, or A and B and C,where any such combinations may contain one or more member or members ofA, B, or C. All structural and functional equivalents to the elements ofthe various aspects described throughout this disclosure that are knownor later come to be known to those of ordinary skill in the art areintended to be encompassed by the claims. Moreover, nothing disclosedherein is intended to be dedicated to the public regardless of whethersuch disclosure is explicitly recited in the claims. No claim element isto be construed as a means plus function unless the element is expresslyrecited using the phrase “means for.”

It should be appreciated to those of ordinary skill that various aspectsor features are presented in terms of systems that may include a numberof devices, components, modules, and the like. It is to be understoodand appreciated that the various systems may include additional devices,components, modules, etc. and/or may not include all of the devices,components, modules etc. discussed in connection with the figures.

The various illustrative logics, logical blocks, and actions of methodsdescribed in connection with the embodiments disclosed herein may beimplemented or performed with a specially-programmed one of a generalpurpose processor, a digital signal processor (DSP), an applicationspecific integrated circuit (ASIC), a field programmable gate array(FPGA) or other programmable logic device, discrete gate or transistorlogic, discrete hardware components, or any combination thereof designedto perform the functions described herein. A general-purpose processormay be a microprocessor, but, in the alternative, the processor may beany conventional processor, controller, microcontroller, or statemachine. A processor may also be implemented as a combination ofcomputing devices, e.g., a combination of a DSP and a microprocessor, aplurality of microprocessors, one or more microprocessors in conjunctionwith a DSP core, or any other such configuration. Additionally, at leastone processor may comprise one or more components operable to performone or more of the steps and/or actions described above.

Further, the steps and/or actions of a method or algorithm described inconnection with the aspects disclosed herein may be embodied directly inhardware, in a software module executed by a processor, or in acombination of the two. A software module may reside in RAM memory,flash memory, ROM memory, EPROM memory, EEPROM memory, registers, a harddisk, a removable disk, a CD-ROM, or any other form of storage mediumknown in the art. An exemplary storage medium may be coupled to theprocessor, such that the processor can read information from, and writeinformation to, the storage medium. In the alternative, the storagemedium may be integral to the processor. Further, in some aspects, theprocessor and the storage medium may reside in an ASIC. Additionally,the ASIC may reside in a user terminal. In the alternative, theprocessor and the storage medium may reside as discrete components in auser terminal. Additionally, in some aspects, the steps and/or actionsof a method or algorithm may reside as one or any combination or set ofcodes and/or instructions on a machine readable medium and/or computerreadable medium, which may be incorporated into a computer programproduct.

In one or more aspects, the functions described may be implemented inhardware, software, firmware, or any combination thereof. If implementedin software, the functions may be stored or transmitted as one or moreinstructions or code on a computer-readable medium. Computer-readablemedia includes both computer storage media and communication mediaincluding any medium that facilitates transfer of a computer programfrom one place to another. A storage medium may be any available mediathat can be accessed by a computer. By way of example, and notlimitation, such computer-readable media can comprise RAM, ROM, EEPROM,CD-ROM or other optical disk storage, magnetic disk storage or othermagnetic storage devices, or any other medium that can be used to carryor store desired program code in the form of instructions or datastructures and that can be accessed by a computer. Also, any connectionmay be termed a computer-readable medium. For example, if software istransmitted from a website, server, or other remote source using acoaxial cable, fiber optic cable, twisted pair, digital subscriber line(DSL), or wireless technologies such as infrared, radio, and microwave,then the coaxial cable, fiber optic cable, twisted pair, DSL, orwireless technologies such as infrared, radio, and microwave may beincluded in the definition of medium. Disk and disc, as used herein,includes compact disc (CD), laser disc, optical disc, digital versatiledisc (DVD), floppy disk and Blu-ray disc where disks usually reproducedata magnetically, while discs usually reproduce data optically withlasers. Combinations of the above should also be included within thescope of computer-readable media.

While aspects of the present disclosure have been described inconnection with examples thereof, it will be understood by those skilledin the art that variations and modifications of the aspects describedabove may be made without departing from the scope hereof. Other aspectswill be apparent to those skilled in the art from a consideration of thespecification or from a practice in accordance with aspects disclosedherein.

What is claimed is:
 1. A display device, comprising: a first monolithicmicro light-emitting diode (MicroLED) projector configured to generate afirst monochrome image in a first color; a second monolithic MicroLEDprojector configured to generate a second monochrome image in a secondcolor; a third monolithic MicroLED projector configured to generate athird monochrome image in a third color; an optical waveguide including:a first in-coupling grating region physically aligned with the firstmonolithic MicroLED projector and configured to receive the firstmonochrome image, a second in-coupling grating region physically alignedwith the second monolithic MicroLED projector and configured to receivethe second monochrome image, the first and second in-coupling gratingregions imparting an equivalent phase change to light reflectingtherefrom, a third in-coupling grating region physically aligned withthe third monolithic MicroLED projector and configured to receive thethird monochrome image, the third in-coupling grating region imparting aphase change different than the equivalent phase change to lightreflecting therefrom, and an out-coupling grating region configured torelease from the optical waveguide light from the first, second, andthird monolithic MicroLED projectors as an expanded image replicating incombination the first, second, and third monochrome images.
 2. Thedisplay device of claim 1, wherein the first monolithic MicroLEDprojector generates the first monochrome image in only red, wherein thesecond monolithic MicroLED projector generates the second monochromeimage in only blue, and wherein the third monolithic MicroLED projectorgenerates the third monochrome image in only green color tone.
 3. Thedisplay device of claim 1, wherein the first in-coupling grating region,the second in-coupling grating region, and the third in-coupling gratingregion are configured to independently receive the first monochromeimage, the second monochrome image, and the third monochrome image,respectively, and wherein the optical waveguide further includes aplurality of diffractive optical elements configured to combine thefirst monochrome image, the second monochrome image, and the thirdmonochrome image to form a final image.
 4. The display device of claim1, wherein the first in-coupling grating region of the optical waveguideincludes a first grating structure, wherein the second in-couplinggrating region of the optical waveguide includes a second gratingstructure, and wherein the third in-coupling grating region of theoptical waveguide includes a third grating structure.
 5. The displaydevice of claim 4, wherein the first grating structure, the secondgrating structure, and the third grating structure are arranged suchthat light associated with each of the first monochrome image, thesecond monochrome image, and the third monochrome image overlaps withinthe optical waveguide to produce a final image.
 6. The display device ofclaim 1, wherein the first and second monolithic MicroLED projectors arephysically positioned at a first side of the optical waveguide such thatlight from the first and second monolithic MicroLED projectors isprojected towards the first in coupling grating region, and wherein thethird monolithic MicroLED projector is physically positioned at asecond, opposite side of the optical waveguide such that light from thethird monolithic MicroLED projector is projected towards the secondin-coupling grating region.
 7. The display device of claim 1, whereinthe optical waveguide has a plurality of internally reflective surfacesto enable light rays of a plurality of different colors generated byfirst, second, and third monolithic MicroLED projectors to propagatethrough a substrate of the optical waveguide by total internalreflection.
 8. The display device of claim 1, wherein the display devicecomprises a head mounted display (HMD) device.
 9. The display device ofclaim 8, wherein the first monolithic MicroLED projector and the secondmonolithic MicroLED projector are positioned near a temple portion ofthe HMD device, and wherein the third monolithic MicroLED projector ispositioned near a nasal portion of the HMD device.
 10. The displaydevice of claim 8, wherein the first monolithic MicroLED projector andthe second monolithic MicroLED projector are positioned near a nasalportion of the HMD device, and wherein the third monolithic MicroLEDprojector is positioned near a temple portion of the HMD device.
 11. Adisplay device, comprising: a first monolithic micro light-emittingdiode (MicroLED) projector configured to generate a first monochromeimage in a first color; a second monolithic MicroLED projectorconfigured to generate a second monochrome image in a second color; athird monolithic MicroLED projector configured to generate a thirdmonochrome image in a third color; an optical waveguide including: afirst in-coupling grating region physically aligned with the firstmonolithic MicroLED projector and configured to receive the firstmonochrome image, a second in-coupling grating region physically alignedwith the second monolithic MicroLED projector and configured to receivethe second monochrome image, the first and second in-coupling gratingregions imparting an equivalent phase change to light reflectingtherefrom, a third in-coupling grating region physically aligned withthe third monolithic MicroLED projector and configured to receive thethird monochrome image, the third in-coupling grating region imparting aphase change different than the equivalent phase change to lightreflecting therefrom, wherein the third in-coupling grating regionoverlaps with at least one of the first in-coupling grating region orthe second in coupling grating region, and an out-coupling gratingregion configured to release from the optical waveguide light from thefirst, second, and third monolithic MicroLED projectors as an expandedimage replicating in combination the first, second, and third monochromeimages.
 12. A method for displaying an image on a display device, themethod comprising: generating a first monochrome image in a first colorfrom a first monolithic micro light-emitting diode (MicroLED) projector;generating a second monochrome image in a second color from a secondmonolithic MicroLED projector; generating a third monochrome image in athird color from a third monolithic MicroLED projector; receiving, at anoptical waveguide, light inputs from each of the first, second, andthird monolithic MicroLED projectors into a plurality of in-couplinggrating regions of the optical waveguide, such that: a first in-couplinggrating region of the optical waveguide is physically aligned with thefirst monolithic MicroLED projector to receive light corresponding tothe first monochrome image, a second in-coupling grating region of theoptical waveguide is physically aligned with the second monolithicMicroLED projector to receive light corresponding to the secondmonochrome image, the first and second in-coupling grating regionsimparting an equivalent phase change to light reflecting therefrom, anda third in-coupling grating region of the optical waveguide isphysically aligned with the third monolithic MicroLED projector toreceive light corresponding to the third monochrome image, the thirdin-coupling grating region imparting a phase change different than theequivalent phase change to light reflecting therefrom, and releasingfrom an out-coupling region of the optical waveguide, light from thefirst, second, and third monolithic MicroLED projectors as an expandedimage replicating in combination the first, second, and third monochromeimages.
 13. The method of claim 12, wherein the first monolithicMicroLED projector generates the first monochrome image in only red,wherein the second monolithic MicroLED projector generates the secondmonochrome image in only blue, and wherein the third monolithic MicroLEDprojector generates the third monochrome image in only green.
 14. Themethod of claim 12, wherein the first in-coupling grating region, thesecond in-coupling grating region, and the third in-coupling gratingregion are configured to independently receive the first monochromeimage, the second monochrome image, and the third monochrome image,respectively, and wherein the optical waveguide further includes aplurality of diffractive optical elements configured to combine thefirst monochrome image, the second monochrome image, and the thirdmonochrome image to form a final image.
 15. The method of claim 12,wherein the first in-coupling grating region of the optical waveguideincludes a first grating structure, wherein the second in-couplinggrating region of the optical waveguide includes a second gratingstructure, and wherein the third in-coupling grating region of theoptical waveguide includes a third grating structure.
 16. The method ofclaim 15, wherein the first grating structure, the second gratingstructure, and the third grating structure are arranged such that lightassociated with the first monochrome image, the second monochrome image,and the third monochrome image overlaps within the optical waveguide toproduce a final image.
 17. The method of claim 12, wherein the firstmonolithic MicroLED projector and the second monolithic MicroLEDprojector are physically positioned at a first side of the opticalwaveguide such that light from the first and second monolithic MicroLEDprojectors is projected towards a first input grating structure, andwherein the third monolithic MicroLED projector is physically positionedat a second side of the optical waveguide such that light from the thirdmonolithic MicroLED projector is projected towards a second gratingstructure of the optical waveguide, wherein the second side is oppositethe first side.